For its inherent advantages, such as lightweight, low cost, flexibility, and opportunity to cover large surface areas, organic solar cells have attracted more and more attention in both academia and industry. However, the efficiency of organic solar cell is still much lower than silicon solar cells, but steadily rising as it now stands above 8%. The architecture of bulk heterojunction solar cells can improve the performance of organic solar cell a lot, but these improvements are highly dependent on the morphology of photoactive layer. Therefore, by controlling the morphology of photoactive layer, most commonly composed of a P3HT donor polymer and PCBM small molecule, the performance of organic solar cells could be optimized. The use of solvent additives in the solution formulation is particularly interesting, because it is a low cost method of controlling the phase separation of the photoactive layer and possibly removing the need for subsequent thermal and solvent vapor annealing. However, the role of the solvent additive remains not well understood and much debate remains on the mechanisms by which it impacts phase separation. In the first part of this thesis, we investigate the role of the solvent additive on the individual components (solvent, donor and acceptor) of the solution and the photoactive layer both in the bulk solution, during solution-processing and in the post-processing solid state of the film. In the second part of this thesis, we investigate the role of the additive on the blended solution state and resulting thin film phase separation. Finally, we propose a new method of controlling phase separation based on the insight into the role of the solvent additive. In the first part, we used an additive [octandiethiol (OT)] in the solvent to help the aggregation of P3HT in the solution. From the UV-vis experiments, the crystallinity of P3HT in the solutions increased while it decreased in thin films with steady increase of additive concentration. This method could be used for one step, annealing-free fabrication of organic solar cell with high performance. The solution can potentially be used to prepare ink for the large scale roll-to-roll ink-jet printing of P3HT thin films. Secondly, from the experiments it is found that differences in the evaporation rate and solubility of the components of the photoactive layer may be part of the reason for morphological changes. With lower evaporation rate than the host solvent, the additive concentration in the solution keeps increasing with time during the final stages of spin coating. In addition, the phase separation is increased with the increase of additive concentration, as demonstrated by AFM and TEM. By controlling the additive concentration, it is possible to control the phase separation of photoactive layer in pristine device. It is also found that the additive can change the wetting ability of the solvent to produce films with high surface coverage. With this information in hand, we modified the solution process of BHJ layers. A layer of crystals was deposited from the OT-containing solution by postponing the start of the spin coating for several minutes (delay time) after the solution is dropped on the surface of substrate. We found this to be a very effective method of increasing the phase separation and crystallinity of the photoactive materials. This effect was not possible when using oDCB solvent without any additive.

Ink-based semiconductors that come to mind today include conjugated molecules and polymers, colloidal quantum dots, metal halide hybrid perovskites, and transition metal oxides. These materials form an ink (solution/ suspension/ sol-gel) that can be applied and dried in ambient air to form high-quality films for optoelectronic devices. In this study, we will introduce the current understanding of ink-based lead and lead-free hybrid perovskite and perovskite-inspired thin films. Examples will be presented through time-resolved studies of the solidification to link the solid-state microstructure and device figures of merit to the ink’s formulation, drying, and solidification process. The perovskite crystallization kinetics characterized in situ during the solution process indicates an essential role by the inclusion of Cs+ and K+ alkali metal cations in perovskite inks. The film and device characterizations indicate the functions of mixed cation and halides in determining the optoelectronic properties. The further sophisticated design of perovskite inks enables significantly optimized charge dynamics, including exciton separation, inter-grain charge transfer, trap density, charge mobility, and charge collection efficiency. The considerably improved optoelectronic properties lead to higher charge collection efficiency and, therefore, better open-circuit voltage and fill factor for the Cs+-containing 3D perovskite devices in contrast to the control FAPbI3 one. Recent developments in ink formulation and processing that enable scalable ambient fabrication of high-quality perovskite semiconductor films will also be presented. These findings raise the possibility of developing more controlled perovskites for systematically addressing both charge dynamics and degradation mechanisms in concert for the timely commercialization of perovskite solar cells.

The energy demand is increasing very rapidly all over the world. Solar energy is one renewable solution to cover the energy demand. Solar power is a universal green energy source, and we receive from the sun more than ten thousand times energy than it has needed on the earth. This report investigates the electricity generation by using solar PV panels for the given village as well as the transmission systems. The main priority of this report is to calculate the demand electricity of the village, plant design also considering the power losses. Three different scenarios to transmit the generated power to the consumers end were considered and studied. The three different cases and cases are, • Grid connection. • Micro-grid power supply system with full battery storage. • Micro-grid power supply system with partial battery storage. All three system were analyzed based on the technical specifications, power losses during transmission. The all calculation was completed by the help of different software, such as PVGIS, MS excel, different empirical formulas and previous research papers. To complete the calculation this, report also consider a few assumptions. After completing all analysis and calculations, the research outcome was showing that the microgrid power supply system with whole battery backup storage will be the better solution both technically and economically. Photovoltaic (PV) solar cell-based microgrid systems can be one of the most feasible solutions to provide electricity in rural areas. Therefore, this system can play a vital role in Bangladesh to provide electricity in rural areas. In Bangladesh, there are several positive aspects to promote the use of photovoltaics (PV), such as many solar irradiations, low technology and labour cost, and a few subsidies from the government.

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The subject of this master’s thesis is to introduce concentrator photovoltaic systems. Main subject of presented work are photovoltaic cells and their features and characteristics. The work deals with physical fundamentals of solar cells, type of cells and their specifics and discusses possible treatment for achieving better characteristics of concentrator systems. In the practical part is realized measurement and analysis of electrical characteristics of 9 different monocrystalline silicon cells. From those is the most efficient cell chosen for further use as reference cell.

Diagnostic of photovoltaic cells defects is one of the key step in production. This dissertation thesis deals about diagnosis of photovoltaic cells by radiative recombination of electron - hole pairs. This radiative recombination is known as luminescence. Diagnostic methods using this local light emission in infrared region have innovative potential. The method of electroluminescence is one of the most widely used luminescence methods whose modifications are applied across the industry, especially in semiconductors. The main area of this thesis research is focused on non-destructive analysis of radiated infrared radiation of monocrystalline and polycrystalline solar cells in various modifications of standard electroluminescence method. In this research there are used two types of CCD cameras are used as luminescent radiation detectors. Method of photon emission microscopy is used for magnification element. Local light emission inspection by microscopy should have benefit to qualitative evaluation of solar cells defects. Radiation emitted by the solar cell has a wave character. This fact brings the potential of using some of the characteristics of the waves. We are talking about the intensity and mainly about new characterization by polarization during the detection of defects in the solar cell surface. Innovation of the measuring workplace of the standard electroluminescence method to use polarization analysis is one of the goals of this dissertation thesis.

The microplasma discharges in the PN junction local defect micro-regions are as a rule, accompanied by the emission of light. This radiation from solar cell PN junctions was measured by means of a optical fibre connected to the optical input of a photomultiplier. By inching the fibre by means of computercontrolled X-Y plotter above the cell surface a 2-D image of the irradiation local regions has been created. It is seen that a cell of a superficial area of 100 square cm contains a large number of defects, which depends on applied reverse voltage. This method can be a convenient tool for study and diagnostics of optoelectronic devices.

The restoring sources of energy and their development brings the question how these sources can be utilized in the best way. Master`s thesis deals with photovoltaic systems. It describes their history line, actual situation and also brings some expectations in the future. There are mentioned some materials and technologies which are used for its manufacture, conditions of using in practice, advantages and disadvantages and finally a real mobile application of photovoltaic which serves for a production of electricity that is saved in the battery.

This work deals with measuring of very low temperatures during the detection defects of solar cells by photoluminescence method. Liquid nitrogen is used to cooling solar cells. Properties of liquid nitrogen and safety of handling are described in this work. Themperature in cryo area is measured by the thermocouple senzors. A main part of this work was to concept and creation of equipment for themperature controling in cryo technique. This equipment signalling danger scorch in low temperatures. The device was created to complement work place for the detection defects of solar cells by photoluminescence method.

This master’s thesis deals with light induced degradation problems. In theoretical section it describes essentials of PN junction function and next light induced degradation mechanisms of solar cells and its symptoms at solar cell operation. In practical section it deals with set of measurements of solar cells since production of the silicon wafer to the complete solar cell. Selected cells are submitted to light induced degradation, measured dependencies are then evaluated. Degraded samples are subsequently recovered by two ways at high temperature treatment. The issues are evaluated.